Method of and apparatus for casting ingots



July 31, 1928.

1,678,976 J. A. DURFEE METHOD OF AND APPARATUS FOR CASTING INGOTS FiledNov. 20. 1926 2 Sheets-Sheet 1 IN VEN TOR.

. ATTORNEY.

- i ul 31, 1928.

. J. A. DURFEE Y METHOD OF AND APPARATUS FOR CASTING INGOTS Filed Nov.20. 1926 2 Sheets-Sheet 2 INV'ENTOR. BY Jos bhAM DLLW 'v- TrfiEYhPatented July 31, 1928;

UNITED STATES JOSEPH A. DUBIEE, OF BTEUBENFIILE, OHIO.

METHOD AND 'APPABATUS FOB CASTING INGOTBQ Application flled-llfovembera0, 1926. Serial in. 149,692.

My invention relates to the art of casting metal ingots and particularlyto the art of castingsteel ingots and ingots of steel allpgs.

eretofore ingots have been cast in cast iron or steel molds or castings,the metal -duce an ingot mold that may be poured from either beingpoured into the top of the mold or forced thereinto from thebottomthereof,-

the latter requiring relatively expensive apparatus compared with toppoured ingots. When the metal is poured in at the top, occluded bubblesformed, when the stream of molten metal strikes the surface of themolten metal sometimes disposed five or more feet below the pouringspout of the ladle,

depending upon thedepth of the mold, are carried toward the side wallsof themold and are there entrapped in the chilled 'metal adj acent'tothe mold walls which are usually three or four inches in-thickness.

The 'zone of the ingotadjacent to the surface and commonly known as .theskin usually contains countless bubbles or blowv holes which zoneextends inward from the surface about an inch. When the ingot is rolledto form a bloom or slab, the bubbles remain near the surface of thebloom or slaband cause seams on or near the surface which remain in thebar or sheet rolled from the bloom or slabrespectively, with the resultthat the surface thereof is rough and of weakened structure. v

Gases released from the molten metal at the time of "pouring or laterare also entrapped and produce bubbles which also are carried to theside walls by the flowing metal .and there permanently entrapped 1n thechilled metal adjacent to the surface of the x ingot.

' sulphur,

The metalloids such as carbon, manganese, etc..have a tendency to movetoward the center of the ingot, the central portion being the last tocool, and therefore are concentrated near the central zones ofthe ingot.

This segregation of the metalloids causes a non-umform'distribution ofthe metalloids and consequently *the steel of the ingot is not uniformin structure or strength. I

An object of my invention is to produce a method of casting ingotswherein the occluded air bubbles and thereleased gasesare preventedfrom-coming in contact with the side walls of the mold or accumulatingin the vicinity of the side walls thereof.

Another object ofmy invention is. to produce' a process of castingingots wherein segregation of the metalloids is arrested if not entirelyprevented and wherein the isthe top and which will' produce an ingotpractically free ofbubbls and in which the metalloids are uniformlydistributed.

Another object of my invention is to provide an ingot mold for producingan ingot having the above noted characteristics thatmay beadapted toexisting ingot mold. casmgs, thereb usmg specia mold casings. Anotherobject of my invention is to rodu'ce an ingot mold wherein the yiel ofusable steel is increased and wherein the quality thereof is superior tothat produced eliminating the necessityf'ofin the usually employed moldby the present 7 practice of casting. a These and other objects thatwill .be niade apparentthroughout the further description of 'mynvention are attained by means of the process and apparatus hereinafterdescribed and illustrated in the accompanying 'drawings,-wherein Figure1 is a vertical section through an ingot cast inthe usual mold and 'bythe present practice of casting; Fig.2 is a similar view of an ingotcast 1n my im rove'd mold and bymy improved process 0 casting;

' Fig. 3 is WYGI'tlCfll section through a'mold embodying features of myinvention;

4 Fig. 4 1s a plan view of the mold shown in Fig. 3;

Fig. 5 .is a vertical section through the mold shown in Fig. .3,illustrating the phenomena incident to casting an ingot by my improvedprocess; 1

Fig. 6' 1s a vertical section through an modified form of moldconstruction;

-Fi 7 is a transverse section taken on the hue VII-VII of Fig. 6;

Fig. 8 is avertical section of a further modification of an ingot mold;

-Fig. 9 is a transverse section line IXIX of Fig. 8; and

Fig. 10 is. a transverse section through a further modification of ,aningot mold;

Referring to the-drawings, Figs. 1 and 2 represent respectively, anmgotcast in the taken on the no usual moldby thepresent process and aningot in my improved mold by my improved process. The ingot 11 shows inexaggerated form the bubbles and blowholes 12' that are entrapped nearthe surface of the ingot and the segregation. of the metalloids 13 nearthe center is represented by the dots,

the concentration. being greatest near the center of the ingot and nearthe upper end.

' 4. The mold casing is supported on a base plate 16 and the partition15 extends from the top to the bottom of the mold and is provided at itslower edges with notches 17, the purpose of which will hereinafterappear.

The walls of mold casings are usually three or four inches in thicknessand consequently are not fused by the molten metal poured into the mold.The partition 15 is preferably of the same metal composition as that tobe poured in the mold and the thickness of the partition walls is suchthat thepartition will fuse after it has beefi immersed in the moltenmetal a predetermined time, the time being determined by the thicknessof the plates andthe temperature of the metal.

The partition is preferably spaced about three inches from the sidewalls of the mold and is centered and supported within the mold byspacers 18 and 19, the latter extending over the upper edges of the moldwalls The operation of the process is illustrated in Fig. 5 wherein themold 14 is shown about half fullof molten metal which is being pouredfrom the spout .of a ladle 21. vWhen 1 the first molten metal was.poured into the moldit flowed under the edges of the partition throughthe notches 17, and thereafter 'themtal flowing to the side walls of themold casing was caused first to'descend under the lower edges of thepartition and thence upward' between the partition and the side walls ofthe moldcasin' -The occludedbubbles12 whic are caused by the column ofmolten metal striking the surface of the molten metal within the mold,

- rise rapidly and the relatively slow down ward movement of the metalwithin the artition as it flows beneath the under e ges thereof, permitsthe bubbles to rise clear of the mass before the-metal flows under thepartition. Therefore the occluded bubbles are released and cannot comein contact with the side walls of the mold where the metal is firstchilled andsolidified.

Because the lower edgesof the partition come first in contact with themolten metal, they are the first to fuse, and the thickness thereof issuch that they withstand the heat suflicient time without fusing tomaintain a portion of the partition always below the surface of themolten metal as indicated in Igig. 5, and well below the zone of thebubles.

The metal therefore must flow downward before it can rise between thepartition and the mold walls, thus clearing it of occluded bubbles dueto pouring of the metal. Molten steel, at the temperature at which it istaken from'the furnace, contains gases in solution such as carbonicacid, nitrogen, hydrogen and other elements. When the metal cools, thesegases are separated or released in the form of minute bubbles. Whenmetal is poured into the usual ingot mold, gases are released inthemetal while the latter is in *a. molten state due to reduction intempera- These bubblesidiifer from the occluded adjacent the walls, themetal at this pointsolidifies before the bubbles have had opportunity torise to the surface. It is an obect of my invention to cause uniformcooling of the metal to the temperature at which the gases. areseparated or released as the metal is being poured into the mold and toprovide suflicient time-for them to rise to the sur-' face before theyactually come into the vicinity of the side walls of the mold. By cansing the metal poured into the mold to descend along and under thepartition or gate where they are cooled thereby, its temper-.

ature is reduced to the point where gas bub- ,bles' are formed andbefore the metal reaches 7 the side walls of the mold the gases areseparated and permitted to rise before flowing to the space between thepartition and the mold walls or other cooled zones.

The partition, however, may be made of such thickness that it will notfuse until the entire ingothas been cast, and in that event, all themetal flowing to the side walls poured. 'The number, size and her/soreof the mold partition. p

The partition also" reduces the temperature of the molten metal in itsimmediate vicinity and this action tends to impedesegregation of themetalloids.

An ingot cools first at the sides incontact with the mold walls, thecenter being the last to solidify.

Such metalloids that have a lower fusion point than the iron, stay in amolten"con dition after the iron molecule has become plastic and thecontraction of the iron molecule tends to squeeze the me'talloidstowards its hottest side which is in the direction of the center of theingot. As the metal solidimust flow downward under the fies themetalloids move toward the center of the ingot, and ingots cast underpresent conditions are found to contain a, greater density of metalloidsnear the center.

The cooling action of the partition within the mass causes the ingot tobe cooled more uniformly, and consequently, the tendency to move thenietalloids to the center is min1- mized, with the result that they aremore uniformly distributed throughout the mass Jposed inconcentricspaced relation within the mold casing 14 and centered by spacers 18 and19. The lower edges are notched to" permit initial-flow of molten metalunder the lower edges,"the metal being poured into the inner partitionand permitted to flow upward between the partitions and be tween theouter partition and the side wall. In this form, there is an increasedrefining or bubble eliminating action, and a more uniformly distributedcooling medium tending to arrest segre ation of the metallolds. It willbe seen that y proper distribution of the partitions'and the mass of thepartitions, substantially uniform cooling can be accomplished andsegregation substantially arrested.

Fig. -8, shows a further =modi-ficat1on wherein in place of the twoinner partitions shown in 'Fig. 6, metal rods 23 are substituted tocause uniform cooling of the mass.

The rods are supported on a late 24 having an opening 25 through whicthe-metal is osition of the rods. may be varied to obtaln unifornicooling action, and to insure fusion thereof before theingot metalsolidifies; The partition 15 functions in the manner of the moldillustrated in Figs. 3, 4' and 5, and may be perforated. I

The partition walls may be made of sheet metal raving openings orperforations or of steel wire gauze as shown in Fig. 10

wherein a cylindrical partition; made of steel, gauze wire is employed.The mainflow of molten metal is beneath the lower edge of the screen,and the coolin action of the screen tends to arrest segreg ion of themetalloids.

It will be understood, that the screens or partitions are preferablymade of metal similar to that being poured and that the temperature ofthe metal is sufiicient to fuse the rods, with the metal of the ingot,the result being "an ingot-of homogeneous structure throughout,substantially free of blowholes and bubbles andof substantially uni-'form composition. By reason of this process, more uniform steel isproduced and the yield per ingot is materially-increased.

To assistin the internal cooling action of the devices above described,pieces of metal scrap may be placed in the mold as the pouringprogresses, thereby reducing the,

temperature of the metal in the interior of the ingot as it is beingpoured and causin 1 a substantially uniform cooling action an evendistribution of the metalloids.

WVhile I have described my process and have shown several modificationsofthe 2. The process of casting ingots in amold.

which consists in placing a partition within the mold and in pouringmolten metalinto the mold on one side of the partition and at atemperature capable of melting the partition before the-metal solidifiesand whereby the. metal is caused to-flowunder the sub- 'merged unmeltedportion of the partition to the other side thereof. v

3. The process ofv casting ingots in a mold which consists in placing aplurality of screens within the mold for dividing the mold intoaplurality of substantially concentric compartments, and in pouring themolten metal into the inner compartment whereby it is caused to flowunderthe 125 screens to the other compartments.

4. The process of casting ingots in a mold which consists in placinwithin the mold fusible metal and in distrlbuting it throughout theinterior of the mold, and in pouring molten metal into the mold at atemperature sufficient to'fuse the fusible metal before the molten metalsolidifies.

5. An ingot mold comprising a mold shell of sufficient mass to preventfusion by the molten metal poured therein and fusible metal supportedwithin the" mold adapted to be fused by the molten metal but constitutedto remain intact beneath the surface of the metal durin' the pouringoperation.

-6.' An ingot mol comprising a relatively nonfusible mold shell andhaving fusible cooling metal supported therein adapted to be fused bythe molten metal poured into the mold but constituted to remain intactbeneat-h the surface of the metal for a, predetermined time during thepouring operation.

7. An ingot mold comprising a mold casing and fusible partitions thereinadapted to be fused by the molten metal poured therein but constitutedto remain intact below the surface of the metal a predetermined distanceduring the pouring opcration.

8. An ingot mold comprising a mold casing andfusible metal directingpartitions therein. v

9. 'An in otmold comprising a mold casing and a usible partition withinthe mold for directing molten metal downward to a predetermined pointbelow the surface ofthe metalbefore it reachesthe side walls of thecasing. 1

10; An ingot mold comprising a mold casoreen ing and a fusible partitionwithin the mold agaplted to remain intact below. the surface 0 tinternally.

11. An ingot mold comprising a mold casing and a fusible cooling agentwithin'the e metal and toeventually fuse for directing the molten metaland for cooling it mold adapted to remain intact below the 13. An ingotmold comprising a mold casing and a pluralityoffuible partitionsdividing' the mold into a plurality of concentric' communicatingcompartments.

14:. An ingot mold comprising a mold casing and a fusible perforatepartition dividing the mold into a plurality of communieatingcompartments.

15. The process of casting metal ingots in a mold which consists inintroducing rela-' tively cold unfused fusible metal members therein forquickly cooling the metal and in pourin the metal into the mold and incontact with the fusible metal members.

.In testimony whereof, I have hereunto subscribed my name this 21st dayof Coteber, 1926. I JOSEPH A. DURFEE.

